The preparation and use of polymer resin encapsulated metal oxides, particularly silica, in textile sizings to promote fiber to fiber cohesion has been demonstrated in U.S. Pat. Nos. 4,728,679 and 4,997,862. These encapsulated colloidal materials, although effective sizing agents for textiles, particularly in combination with other sizing agents such as starch or polyvinyl alcohol, have found limited commercial application. Use has been limited to situations in which the encapsulated material can be formed on site immediately prior to its application at elevated temperature onto warp yarn. This procedure was required to minimize the period of time during which the natural tendency of the metal oxide particles to disassociate and form large 3-dimensional inorganic polymer networks can occur. When a 3-dimensional inorganic polymer network is formed, it destroys the desirable small particle size and high surface area features of the colloidal metal oxide particles and generates larger particles which are both abrasive to metal and ceramic surfaces and contain areas of entrapped encapsulating polymer resin within the 3-dimensional inorganic polymer network.
Generally, the aqueous polymer resin encapsulated colloidal metal oxide compositions of U.S. Pat. Nos. 4,728,679 and 4,997,862 containing about 20% by weight and higher solids are stable at room temperature for only a few days before substantial viscosity build-up occurs, leading to complete gelation within 2-3 weeks. While, the encapsulated colloidal particle complex can be prepared in dry form by spray drying, doing so is expensive and the resulting material is of very low density which restricts packaging to 75-80% of standard packaging weights.
Accordingly, it is an object of the present invention to enhance the stability of polymer resin encapsulated colloidal metal oxide particles in a liquid system, both at room temperature and at elevated temperature.
It is a further object to enhance the stability of the encapsulated colloidal metal oxide particles while maintaining and/or improving the performance of the particles as textile sizing agents.
These and still further objects will be apparent from the following description of the present invention.